Geologists dredge up dinosaur from the deep
Core from the ocean floor may hold rare plateosaur find.
Jørn Hurum has hit a scientific jackpot twice. First by finding a dinosaur bone in an oil-drill core sample found off the North Sea, and then by being able to identify the dinosaur from that one tiny sample.
"It really was a lucky draw," says Hurum, a palaeontologist at the University of Oslo's Natural History Museum in Norway.
"It is rare for any ocean drilling to encounter macrofossils," agrees geologist John Tarduno, from the University of Rochester, New York, adding that most core samples do yield some microorganisms and marine plant life. But not dinosaurs. Even if a ship were to park directly above a dinosaur skeleton it's still not a sure thing that it would actually dig a bit up, as the drill bits on these kinds of trips are typically just ten centimetres in diameter. "It's like finding a needle in 10 haystacks," says Hurum.
The curious sample was found in 1997 by two geologists who were drilling into sandstone reservoirs along the Snorre field in the North Sea in search of oil. In one of the cores, pulled up from 2,615 metres below the seabed, they found a four-centimetre-wide hollow circular structure embedded in the brown sediment. No one was sure what it was; some geologists thought it was a piece of plant.
Discouraged, the geologists kept the fragment to themselves for a while and showed it to inquisitive graduate students. The fragment was eventually passed down in 2003 to Hurum, who immediately thought it looked just like a hollow bone from a meat-eating dinosaur. Hurum took it to one of his colleagues, who happened to be working with such dinosaur bones, to see whether there was a match.
A microscopic examination of the bone showed that it looked very much like that of a Plateosaurus. "The specimens matched completely," Hurum says. "You usually can't identify a dinosaur from a small sample." But in this case, he says, the match is so good that he is sure of the identification. He can even tell that the bone fragment probably comes either from the lower arm or lower leg bone.
Others aren't quite so confident about the precise identity of the rare find; some palaeontologists say it is hard to pin down an exact species from microscopic structure studies.
The Plateosaurus was a prevalent dinosaur species in Europe 210 to 195 million years ago, at the end of the Triassic period. During this period, Greenland and Norway were connected by land and there was no North Sea.
The Plateosaurus would have stood about ten metres long and weighed up to four tonnes.
Three plateosaur skeletons have been found in Greenland and several throughout Europe. But this is the first piece of a Plateosaurus to be found in (or at least near) Norway.
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- Hurum J., et al. Norweg. J. Geol., 86. 93 - 99 (2006).